The entertainment industry uses fog as a special effect in a number of situations, especially during movie productions. Typically, liquid nitrogen or solid carbon dioxide is heated upon demand, such as by combining the nitrogen with steam in a fog generator. However, both of these cryogenic substances will degrade the surrounding atmosphere, eventually below safe limits if prompt mitigating action is not taken. Fog generators on movie production sets usually are accompanied by large fans which are periodically turned on, after the fog generators are turned off, to sweep away the accumulated nitrogen or carbon dioxide to protect actors and support personnel.
Because such conventional fogs present breathing hazards, their use during movie productions must be minimized. Photographers must estimate filming characteristics of a scene, and then adjust settings quickly after the fog generators are activated. More than one film take is generally required for each filming event which greatly increases personnel costs and efforts. The sweep fans must be utilized between takes to circulate fresh air over the scene which wastes further time and energy.
Synthetic liquid air has been manufactured and used to store perishable food stuffs such as disclosed in EP657107 (Garrett et al.) and EP774634 (Paige). Storage of multi-component cryogenic liquid is described in U.S. Pat. No. 5,571,231 (Lee). Use of synthetic liquid air as a chilling fluid for refrigeration is further discussed in an article entitled "The Air that I Breathe" (1997).
It is also known to produce synthetic liquid air for downhole injection at oil fields by adding liquid oxygen and then liquid nitrogen into a transport tractor trailer and driving the trailer around a yard to mix the load. Fifteen sudden stops from low speed is recommended to mix the liquids sufficiently for downhole injection and combustion purposes.